From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 net/ipv4/netfilter/nf_defrag_ipv4.c | 129 ++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 net/ipv4/netfilter/nf_defrag_ipv4.c

(limited to 'net/ipv4/netfilter/nf_defrag_ipv4.c')

diff --git a/net/ipv4/netfilter/nf_defrag_ipv4.c b/net/ipv4/netfilter/nf_defrag_ipv4.c
new file mode 100644
index 000000000..c88b7d434
--- /dev/null
+++ b/net/ipv4/netfilter/nf_defrag_ipv4.c
@@ -0,0 +1,129 @@
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/types.h>
+#include <linux/ip.h>
+#include <linux/netfilter.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <net/route.h>
+#include <net/ip.h>
+
+#include <linux/netfilter_bridge.h>
+#include <linux/netfilter_ipv4.h>
+#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+#include <net/netfilter/nf_conntrack.h>
+#endif
+#include <net/netfilter/nf_conntrack_zones.h>
+
+static int nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
+{
+	int err;
+
+	skb_orphan(skb);
+
+	local_bh_disable();
+	err = ip_defrag(skb, user);
+	local_bh_enable();
+
+	if (!err) {
+		ip_send_check(ip_hdr(skb));
+		skb->ignore_df = 1;
+	}
+
+	return err;
+}
+
+static enum ip_defrag_users nf_ct_defrag_user(unsigned int hooknum,
+					      struct sk_buff *skb)
+{
+	u16 zone = NF_CT_DEFAULT_ZONE;
+
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+	if (skb->nfct)
+		zone = nf_ct_zone((struct nf_conn *)skb->nfct);
+#endif
+
+#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
+	if (skb->nf_bridge &&
+	    skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)
+		return IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone;
+#endif
+	if (hooknum == NF_INET_PRE_ROUTING)
+		return IP_DEFRAG_CONNTRACK_IN + zone;
+	else
+		return IP_DEFRAG_CONNTRACK_OUT + zone;
+}
+
+static unsigned int ipv4_conntrack_defrag(const struct nf_hook_ops *ops,
+					  struct sk_buff *skb,
+					  const struct nf_hook_state *state)
+{
+	struct sock *sk = skb->sk;
+	struct inet_sock *inet = inet_sk(skb->sk);
+
+	if (sk && (sk->sk_family == PF_INET) &&
+	    inet->nodefrag)
+		return NF_ACCEPT;
+
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+#if !IS_ENABLED(CONFIG_NF_NAT)
+	/* Previously seen (loopback)?  Ignore.  Do this before
+	   fragment check. */
+	if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
+		return NF_ACCEPT;
+#endif
+#endif
+	/* Gather fragments. */
+	if (ip_is_fragment(ip_hdr(skb))) {
+		enum ip_defrag_users user =
+			nf_ct_defrag_user(ops->hooknum, skb);
+
+		if (nf_ct_ipv4_gather_frags(skb, user))
+			return NF_STOLEN;
+	}
+	return NF_ACCEPT;
+}
+
+static struct nf_hook_ops ipv4_defrag_ops[] = {
+	{
+		.hook		= ipv4_conntrack_defrag,
+		.owner		= THIS_MODULE,
+		.pf		= NFPROTO_IPV4,
+		.hooknum	= NF_INET_PRE_ROUTING,
+		.priority	= NF_IP_PRI_CONNTRACK_DEFRAG,
+	},
+	{
+		.hook           = ipv4_conntrack_defrag,
+		.owner          = THIS_MODULE,
+		.pf             = NFPROTO_IPV4,
+		.hooknum        = NF_INET_LOCAL_OUT,
+		.priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
+	},
+};
+
+static int __init nf_defrag_init(void)
+{
+	return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
+}
+
+static void __exit nf_defrag_fini(void)
+{
+	nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
+}
+
+void nf_defrag_ipv4_enable(void)
+{
+}
+EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
+
+module_init(nf_defrag_init);
+module_exit(nf_defrag_fini);
+
+MODULE_LICENSE("GPL");
-- 
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